1. Field of the Invention
The present invention relates generally to a recliner adjuster attached to, for example, an automobile seat for appropriately adjusting the inclination of a seat back with respect to a seat cushion and, in particular but not exclusively, to a backlash reducing structure for a recliner adjuster.
2. Description of the Related Art
In the recliner adjuster disclosed in Japanese Utility Model Publication (examined) No. 42-7950, a sector gear is fixed to a seat back while a worm gear, which can be freely engaged with and disengaged from the sector gear, is attached rotatably to a seat cushion. The worm gear is connected to an operation shaft and, by pulling the operation shaft in the axial direction thereof and by subsequently lifting it up, the engagement between the worm gear and sector gear is released. When a load is applied to the seat back in this state, the seat back tilts and the inclination thereof can be altered quickly. When the hand is released from the operation shaft, the worm gear and sector gear reengage to hold the seat back in that position. In addition, if fine adjustment of the inclination of the seat back is required, when the operation shaft is rotated to rotate the worm gear, the sector gear held in engagement with the worm gear rotates gradually whereby the seat back can be altered smoothly to the desired inclination.
Recently, as disclosed in Japanese Laid-Open Patent Publication (unexamined) No. 10-217817, a recliner adjuster was proposed in which a sector gear and a worm gear having a lead angle greater than the friction angle are respectively attached to a seat back and a seat cushion, and in which by tilting the seat back, the worm gear is caused to rotate by way of the sector gear whereby the inclination of the seat back is altered as appropriate.
However, there are problems in a recliner adjuster having a sector gear and a worm gear which engage with each other in that abnormal noise is generated by the backlash which represents the play between the teeth surfaces of the sector gear and worm gear, and in that the stability of the seat back and seating comfort are deteriorated.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a backlash reducing structure for a recliner adjuster which has a simple configuration and with which the stability and seating comfort are improved by reducing the backlash.
In accomplishing the above and other objectives, the backlash reducing structure according to the present invention includes a worm gear attached rotatably to a seat cushion, a sector gear fixed to a seat back and held in engagement with the worm gear, and a pressing member for pressing the sector gear to the worm gear to reduce backlash therebetween. This construction improves the stability and seating comfort of a recliner.
The backlash reducing structure further includes a bracket attached to the seat cushion and having a tapered groove formed therein, wherein the pressing member includes a roller attached rockingly to the sector gear and inserted loosely in the tapered groove. The roller is biased along an edge of the tapered groove to press the sector gear to the worm gear. With this simple construction, the backlash is positively reduced.